Wrought iron plates of 6 feet (1.8m) long and 2 feet (60cm) wide. The thickest plates 7/8 inch (2cm) near the keel, with 3/8 inch (1cm) higher up the hull. The plates are riveted to ribs 18 inches (45cm) apart. 3.5 years to build with 1040 tons of iron and 370 tons of wood SS Great Britain launched in 1843 Great Western Dockyard 1970 returned to Bristol after lying in Falkland Islands. Wrought Iron hull and screw propeller. 160 years old covered more than 1 million ocean miles when retired in 1933